U.S. patent number 5,668,421 [Application Number 08/417,948] was granted by the patent office on 1997-09-16 for pressurized air-gap guided active linear motor suspension system.
This patent grant is currently assigned to E. B. Eddy Forest Products Ltd.. Invention is credited to Herbert E. Gladish.
United States Patent |
5,668,421 |
Gladish |
September 16, 1997 |
Pressurized air-gap guided active linear motor suspension
system
Abstract
The invention relates to an active linear induction motor system
that has particular advantage with a SAILRAIL.RTM. air guided and
supported air bearing system. In this case the secondary for the
motor is the support rail, which rail can have a convex or a
concave operating surface, is electrically conductive, and has
ferromagnetic material in close proximity to the operating surface.
The primary for the motor is found in a runner which cooperates
with the rail and supports the load to be carried in the system.
The primary includes a plurality of laterally adjacent,
longitudinally extending and articulated ferromagnetic laminations
having a longitudinally toothed surface that is transversely
arcuate to be complementary to the rail operating surface.
Electrical windings are wound about selected groups of teeth of the
laminations as a LIM primary. A compliant pad adjacent the
laminations is capable of deformation under load and at least
partial recovery after load removal. Electrical power is
continuously provided to the primary as it moves along the rail and
polyphase electrical current is fed to the electrical windings.
Cooling fluid is continuously provided to the laminations during
operation of the primary. The system also provides pressurized
fluid at high velocity into the space between the rail operating
surface and the compliant pad, to support the primary member above
the operating surface and to provide a minute pressurized magnetic
and suspension gap between the primary and secondary members for
efficient linear motor operation.
Inventors: |
Gladish; Herbert E. (Ottawa,
CA) |
Assignee: |
E. B. Eddy Forest Products Ltd.
(Ottawa, CA)
|
Family
ID: |
23656010 |
Appl.
No.: |
08/417,948 |
Filed: |
April 6, 1995 |
Current U.S.
Class: |
310/12.11;
104/23.2; 310/12.21; 310/12.29; 310/12.31 |
Current CPC
Class: |
F16C
32/06 (20130101); F16C 29/025 (20130101); H02K
41/025 (20130101); B60L 13/10 (20130101); B66B
11/0407 (20130101); B60L 2200/26 (20130101); H02K
9/04 (20130101); H02K 9/10 (20130101); H02K
7/08 (20130101); F16C 2326/58 (20130101) |
Current International
Class: |
B66B
11/04 (20060101); B60L 13/00 (20060101); B60L
13/10 (20060101); H02K 41/025 (20060101); H02K
7/08 (20060101); H02K 9/10 (20060101); H02K
9/04 (20060101); H02K 9/00 (20060101); B60L
013/00 (); H02K 041/00 (); B65G 015/04 () |
Field of
Search: |
;310/12
;104/23.2,290,291,292,294,138.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
1280991 |
|
Mar 1991 |
|
CA |
|
3402143 |
|
Aug 1984 |
|
DE |
|
3536151 |
|
Apr 1986 |
|
DE |
|
2165515 |
|
Apr 1986 |
|
GB |
|
WO93/05565 |
|
Mar 1993 |
|
WO |
|
Primary Examiner: Stephan; Steven L.
Assistant Examiner: Jones; Judson H.
Attorney, Agent or Firm: Jones, Tullar & Cooper,
P.C.
Claims
I claim:
1. An active linear induction motor (LIM) propulsion system
comprising: a passive secondary in the form of at least one
elongated rail member having transversely arcuate operating surface
means; an active primary member for interaction with the rail
member; and means for providing pressurized fluid between said rail
operating surface means and said primary member to support said
primary member above said operating surface means and to maintain a
magnetic air gap between said primary member and said operating
surface means; wherein:
(a) said rail member includes electrically conductive and
ferromagnetic means in close proximity to said operating surface
means over the length thereof;
(b) said primary member includes: a plurality of laterally
adjacent, longitudinally extending and articulated ferromagnetic
laminations, said laminations having a longitudinally toothed
surface that is transversely arcuate to be complementary to said
rail operating surface means; electrical windings wound about
selected groups of teeth of said laminations as a LIM primary;
compliant means adjacent said laminations, capable of deformation
under load and at least partial recovery after load removal; power
means for obtaining electrical power continuously as said primary
moves along said rail and supplying polyphase electrical current to
the electrical windings; and cooling means contained in said
primary member for continuously providing cooling fluid to said
laminations during operation of the primary member; and
(c) said means for providing pressurized fluid is adapted to inject
pressurized fluid at high velocity into the space between said rail
operating surface means and said compliant means, to support said
primary member above said operating surface means and to provide a
minute pressurized magnetic and suspension gap between the primary
and secondary members for efficient linear motor operation.
2. The system of claim 1 wherein said rail member is cylindrical in
cross-section, said operating surface means is convex, said
electrically conductive means is carried on said operating surface
means, and said means for supplying pressurized fluid is contained
in said primary member.
3. The system of claim 1 wherein said rail member has a
transversely concave operating surface means, said ferromagnetic
means is provided within said rail member, a plurality of small
diameter nozzles extend from the interior of said rail member to
the exterior thereof, exiting at said operating surface means, and
said means for providing pressurized fluid supplies the pressurized
fluid to flow through selected nozzles to the operating surface
means when said primary member is in the vicinity of such selected
nozzles.
4. A core for a primary of an active linear induction motor
comprising: a plurality of longitudinally adjacent modules; each of
said modules including a plurality of juxtaposed longitudinally
extending ferromagnetic plates, each of said plates including a
plurality of rectangular teeth extending along a longitudinal edge
thereof with adjacent teeth being separated by a rectangular slot,
said plates being positioned relative to each other to define a
plurality of longitudinally spaced core teeth composed of laterally
adjacent plate teeth, each core tooth having a transversely arcuate
operating surface complementary to a rail supporting and guiding
surface; means at each end of each module for interengaging
longitudinally adjacent modules to permit limited rotational
articulation of one module relative to the adjacent module or
modules; and electrical windings wound around selected groups of
said core teeth of the interengaged modules to create a plurality
of separate, longitudinally adjacent core poles, the windings of
every third pole being electrically connected together to define
three individual sets of such poles over the length of said
core.
5. The core of claim 4 wherein selected ones of the ferromagnetic
plates of each module have a portion thereof extending upwardly of
the others of the juxtaposed ferromagnetic plates within the
module, opposite to said core teeth, said extending portions
serving to help dissipate heat generated during operation of said
primary.
6. The core of claim 5 wherein each plate of each module has a
generally semicircular protrusion extending from the forward or the
rearward edge thereof and a generally semicircular recess extending
into the rearward or the forward edge thereof respectively, each
protrusion of a plate of one module being adapted for rotational
reception in the recess of a longitudinally aligned plate of an
adjacent module.
7. The core of claim 6 wherein the forward edges of laterally
adjacent plates of each module are provided alternately with a
recess and a protrusion respectively.
8. The core of claim 7 including tension means extending around the
interengaged and wound modules to maintain said modules in
interengagement while permitting said limited intermodule
articulation.
9. The core of claim 7 wherein said wound modules, but not the
protrusions and recesses thereof, are encapsulated in a moderately
flexible protective material.
10. The core of claim 9 wherein said material is an epoxy having a
high index of thermal conductivity.
11. The core of claim 6 including a compliant layer extending along
the operating surface of said core, said compliant layer comprising
a filler including a length of multilayered cellulosic material and
a resilient yet flexible cover encasing the filler over the length
thereof.
12. A runner serving as a primary for a fluid bearing linear
induction motor (LIM) propulsion system wherein a secondary for the
system is in the form of an elongated rail having a transversely
convex operating surface such that the runner can be supported and
guided by the secondary on a thin layer of pressurized fluid, said
runner comprising: an elongated housing; electrical motor means
within said housing; a plurality of longitudinally adjacent LIM
operating modules adjacent said housing, each module including a
plurality of longitudinally extending laterally adjacent core
plates defining a transversely concave surface complementary to
said rail operating surface, said modules being interengaged for
limited relative rotational articulation; electrical wiring
suitably wound about the plates of said modules for a LIM primary;
compliant support means attached to said complementary concave
surface of said modules; flexible bag means sealingly supporting
said housing on said modules, said modules being exposed to the
interior of said bag means; means connecting said motor means and
said wiring to electrical power means carried by or adjacent said
rail whereby electrical power can be continuously provided to said
motor means and to said electrical wiring; fluid compression means
within said housing, driven by said motor means for providing
pressurized fluid; heat exchange means within said housing for
cooling the fluid used to extract heat from said operating modules
of said primary; means for continuously circulating heat extraction
fluid from the interior of said bag means to said heat exchange
means and back to said bag means to cool said modules exposed to
the interior thereof; and means for feeding pressurized fluid
produced by said fluid compression means to an operating surface of
said compliant means to provide said thin layer of pressurized
fluid which acts as a fluid bearing in cooperation with said rail
operating surface for supporting and guiding said runner on said
rail and for maintaining a minimum magnetic gap between said runner
and said rail for proper LIM operation.
13. The runner of claim 12 wherein: each of said core plates
includes a plurality of lengthwise alternating rectangular teeth
and slots, said plates being juxtaposed to define a plurality of
longitudinally spaced core teeth composed of laterally adjacent
plate teeth, each core tooth having a transversely concave profile
complementary to the rail operating surface; means are provided at
each end of each plate for interengaging longitudinally adjacent
plates to permit limited rotational articulation of one module
relative to the adjacent module or modules; and said electrical
wiring is wound around selected numbers of said core teeth of the
interengaged modules to create a plurality of separate,
longitudinally adjacent core poles, the windings of every third
pole being electrically connected together to define three
individual sets of such poles over the length of said runner.
14. The runner of claim 13 wherein selected ones of the
ferromagnetic plates of each module have a portion thereof
extending proud of the others of the juxtaposed plates into the
interior of the bag means, said extending portions offering
increased exposure to said heat extraction fluid in the interior of
said bag means and serving to further dissipate heat generated
during operation of said primary.
15. The runner of claim 14 wherein each plate of each module has a
generally semicircular protrusion extending from the forward or the
rearward edge thereof and a generally semicircular recess extending
into the rearward or the forward edge thereof respectively, each
protrusion of a plate of one module being adapted for pivotal
reception in the recess of a longitudinally aligned plate of an
adjacent module.
16. The runner of claim 15 wherein the forward edges of laterally
adjacent plates of each module are provided alternately with a
recess and a protrusion respectively.
17. The runner of claim 16 including tension means extending around
the interengaged and wound modules to maintain said modules in
interengagement while permitting said limited intermodule
articulation.
18. The runner of claim 16 wherein said wound modules, but not said
protrusion and recesses, are separately encapsulated in a
moderately flexible protective material.
19. The runner of claim 18 wherein said material is an epoxy having
a high index of thermal conductivity.
20. The runner of claim 12 wherein said compliant support layer
comprises a filler including a length of multilayered cellulosic
material and a resilient yet flexible cover encasing the filler
over the length thereof.
21. The runner of claim 12 wherein said housing includes louvre
means at each end thereof, forward and rearward radiator means
within the housing adjacent the louvre means, first conduit means
connected to said fluid compression means and passing in front of
said forward radiator means, second conduit means interconnecting
said radiator means, and venturi means at an exit from said forward
radiator means, whereby relatively hot fluid is circulated from the
interior of said bag means through said rearward radiator means,
along said second conduit means and through said forward radiator
means, is cooled at both said radiator means, and is mixed with,
and further cooled by, compressed fluid from said first conduit
means at said venturi means, the cooled fluid flowing into said bag
means and then flowing over the extended portions of said modules
to cool said modules.
22. The runner of claim 21 wherein said fluid is air and including
means for introducing make-up air to said compression means from
the atmosphere.
23. A conveying system for conveying a load between two points
comprising: a linear motor propulsion system as defined by claim 2;
means for supporting the load from said primary member; and means
extending along and adjacent to said rail member for supplying
electrical power to said power means on said primary member;
wherein said rail member extends continuously between said points,
said supporting means includes means for suspending the load below
said rail member, and said power means includes electrical pick-up
means extending between said primary member and said electrical
power supplying means.
24. A conveying system for conveying a load between two points
comprising: a linear motor propulsion system as defined by claim 3;
means for supporting the load by said primary member; and means
extending along and adjacent to said rail member for supplying
electrical power to said power means on said primary member;
wherein said rail member extends continuously between said points,
said supporting means includes deck means for supporting the load
above said rail member, and said power means includes electrical
pick-up means extending between said primary member and said
electrical power supplying means.
25. A conveying system for conveying a load between two points
comprising: a linear motor system as defined by claim 2; a first
said primary member; a second, inverted said primary member
connected to said first primary member and loaded against a second
operating surface means of said rail opposite the first-defined
operating surface means thereof; means extending along said rail
member for supplying electrical power to said power means on one of
said primary members; means carried by said primary members for
supporting the load; and means interconnecting said primary members
for shared power, pressurized fluid and fluid recirculation
provision; wherein said rail member extends continuously between
said points, and said power means includes electrical pick-up means
extending between said one of said primary members and said
electrical power supplying means.
26. A conveying system as defined by claim 25 wherein said rail
member is circular in cross-section, said first-mentioned operating
surface means is an upper external arcuate surface portion of said
rail member, said first primary member is positioned adjacent said
upper surface portion, said second operating surface means is a
lower external arcuate surface portion of said rail member, and
said second primary member is positioned adjacent said lower
surface portion.
27. A conveying system as defined by claim 25 wherein said rail
member is generally C-shaped in cross-section, having an arcuate
internal surface and a slot extending longitudinally along one side
of the rail member, said first-mentioned operating surface means is
an upper internal arcuate surface portion of said rail member, said
first primary member is positioned adjacent said upper surface
portion, said second operating surface means is a lower internal
arcuate surface portion, said second primary member is positioned
adjacent said lower surface portion, said load supporting means
extends externally of said rail member through said slot, and said
electrical power supplying means is positioned adjacent said rail
member internal surface opposite said slot.
28. A conveying system as defined by claim 27 including a pair of
mirror image said C-shaped rail members laterally spaced apart and
canted towards each other with the slots thereof facing each other,
said load supporting means of each pair of primary members being
connected together between the rail members to support a load
thereon.
29. A conveying system for conveying a load between two points
comprising: a linear motor propulsion system as defined by claim 3;
a second rail member having a transversely concave upper surface
extending parallel to said first-defined rail member; a runner
member for air bearing support and guiding on said second runner
member; means for providing pressurized fluid to said second rail
member for communication thereof to the upper surface of said
second rail member; deck means extending between said primary
member and said runner member for supporting a load thereon; and
means extending along and adjacent to said first-defined rail
member for supplying electrical power to said power means on said
primary member; wherein said rail members extend continuously
between said points, and said power means includes electrical
pick-up means extending between said primary member and said
electrical power supplying means.
30. An elevator system comprising: a container member in which
people and/or goods are to be moved generally vertically and a
linear motor propulsion system as defined by claim 2 symmetrically
arranged relative to said container member for moving said
container member generally vertically, each primary member of said
propulsion systems being secured to said container member and the
rail members of said propulsion systems extending parallel and
between vertically spaced apart levels.
31. A rail section serving as a secondary for an active linear
motor propulsion system wherein a primary for the system is
included in a member to be supported and guided by the rail
section, said section comprising: a hollow elongated member of an
electrically conductive non-ferromagnetic material having a
transversely concave operating surface; at least one internal
passageway extending the length of said rail section for receiving
pressurized fluid, said passageway communicating with the
atmosphere by way of a plurality of longitudinally spaced small
diameter nozzles extending through said rail section to open at
said operating surface; and a plurality of ferromagnetic elements
contained within said passageway in close proximity to said
operating surface, said nozzles extending through or past said
ferromagnetic elements.
Description
The present invention relates to linear motor technology in general
and active configuration electromagnetic thrust propulsion systems
using pressurized fluid-film gap suspension and directional guiding
in particular. The invention involves improvements in such
technology as it relates particularly to compliant air-bearing
support and transport of loads on curved profile guideway rails at
high speeds. No mechanical moving parts are required to maintain
the directional guideway guiding or the magnetic gap between the
flexible primary active element and the guideway rail secondary
passive element. The system includes inherent braking and locking
provisions and fluid cooling for high power duty cycle
advantages.
BACKGROUND OF THE INVENTION
Powered guided linear motion can be provided by many means. These
include the use of rodless cylinder or cable cylinder actuators
which offer a number of significant advantages over other
mechanical alternatives such as belts or chains, lead screws or
cam/crank drives. The process of converting rotary motion into
linear motion often necessitates the use of complex mechanical
linkages as well as wheels and sub-assemblies. As a result, the use
of relatively simple rodless or cable cylinders has become quite
common, although some moving and sliding parts having lubrication
requirements are still present. Pneumatic rodless or cable
cylinders do provide a degree of production ease with high
acceleration and speed at low cost. Specialist skills are not
required for operation or construction and installation is
relatively easy and safe. Control and accuracy are now available
with hydraulic power application; however, the advantages of
self-guiding and structural strength with compactness are generally
countered by a limitation to a maximum length of cylinder travel of
only 42 feet.
The use of electromagnetic propelled systems for linear transit is
an alternative of considerable merit and is used extensively for
speedy movement. In many applications high thrust powers are used
over long travel distances. The present state of the art of
electromagnetic propulsion by linear motors is based on technology
which exhibits low efficiencies due to mechanical positioning
complications and other operating requirements which include low
service factors due to heat build-up. Many of these drawbacks are
overcome to a significant degree by the present invention as
described herein which combines the simplicity of guided air-film
suspension with active type electromagnetic propulsion.
Linear motor technology used with air-film suspension is not new.
U.S. Pat. No. 5,128,569 suggests ways of using linear motors whose
widely spaced passive primary units are incorporated directly into
parallel extruded trough-like rails equipped with air nozzles. In
this case the air-bearing suspension maintains a minimal magnetic
air-gap and supports the compliant runners equipped with the linear
motor secondaries. These secondary element runners are attached to
the underside of carrier decks for low friction powered load
transport. The runners basically include a polymer covered
cellulose multiple web winding around a full length core of narrow
width. This assembly exhibits some vertical flexibility with
horizontal stiffness. A generally full length pocket cut into the
bottom of the runner cellulose accommodates curved metallic plates
which provide a secondary linear motor electromagnetic element. The
entire runner assembly possesses the necessary cushioned compliancy
for air-bearing suspension as well as the means for providing
induced current magnetism for linear thrust in co-action with the
widely spaced primary linear motor units of the guideway support
rail(s). The foregoing description of the USA patent is related to
electrically connected passive primary linear motor elements
mounted in air suspension support rails and operating in
conjunction with active secondary linear motor runner elements
which support load carriers and have no external electrical
connections. Passive primary linear motor elements are particularly
suited to applications for simple transport of unit loads on
air-film rails and tracks. No additional mechanical wheels are
required to maintain magnetic air-gap nor are separate guiding or
energy source collectors needed. Possible drawbacks of passive
primary linear motor systems are the need for multiple linear motor
units, and extensive compressed supply air routing over long
distances. Also, the number of linear motor units and the length of
air supply duct required can be very high with associated cost and
pressure drop penalties. For example, in a transport system of a
mile in length, some (528) motors would be required if employing a
10 foot (coast) interval between each rail motor primary unit. The
passive system however has advantages of modular design and hard
wired circuitry with short on-cycle energizing of the motors for
highest thrust powers.
Operating experience with the air-film track passive type primary
linear motor systems has shown that high currents for high thrust
pulses can be attained during the extremely short on-time
energizing of the primary units. The heat produced would be a
severe limiting factor of operation were it not for the full-time
cooling of all motors provided by the suspension compressed air
flowing through the rail linear motor primaries--including motors
in the off-cycle mode. The suspension air flow provides continuous
forced-cooling of the secondary elements as well as the motor
windings by high-density and high-velocity air allowing a high duty
cycle and use of very high momentary overload currents for unique
high thrust generation.
SUMMARY OF THE INVENTION
Whereas passive primary linear motor systems have advantages when a
large number of unit loads are moved over a relatively short
guideway--active or moving primary linear motor systems have
distinct advantages associated with moving a small number of unit
loads over relatively long distances. Active primary systems
require only a single or a minimum number of linear motor primary
units with localized suspension and therefore need only a very
small air supply. In the active primary system it is the support
rail which provides the secondary element for induced electrical
magnetic thrust interaction. The few drawbacks of moving electric
primary elements include a need for continuous or modulating
energizing currents (with associated continuous heat generation)
together with the need for essentially a full guideway length power
collector device.
Present state of the art active type primary linear motors are used
extensively for monorail load movement applications which include
industrial overhead conveyor networks, mainly in automotive
assembly plants. These typically require mechanical support and
guide wheels and relatively complicated braking systems. Support
wheel guiding devices are unsprung and were it not for wear
adjustment provisions there could be damaging contact between the
linear motor elements. Strict maintenance schedules are employed as
described in various patents such as Canadian Patent No. 1,280,991
issued Mar. 5, 1991 to Daifuku Co., Ltd..
All active systems require power collector devices. Most of these
are of the mechanical sliding shoe type with inherent safety,
environmental, and high maintenance drawbacks. The rubbing and
arcing of the electrical contacts greatly contribute to contact
failure and environment ozone duress.
Linear motor primary active (and passive) units are long and narrow
assemblies with wire conductor field coils wound around slotted
steel lamination plates bolted together. These assemblies provide a
longitudinal moving magnetic field when energized with polyphase
electric currents. Generally, such motors are very rigid, except
for that suggested in U.S. Pat. No. 3,547,041 which describes
vertically hinged linear motors to accommodate trolley beam curves
in a generally horizontal plane but for which a means of
maintaining air gap is not defined.
Generally speaking the present invention may be broadly considered
to provide an active linear inductions motor (LIM) propulsion
system comprising: a passive secondary in the form of at least one
elongated rail member having transversely arcuate operating surface
means; an active primary member for interaction with the rail
member; and means for providing pressurized fluid between the rail
operating surface means and the primary member to support the
primary member above the operating surface means and to maintain a
magnetic air gap between the primary member and the operating
surface means; wherein:
(a) the rail member includes electrically conductive and
ferromagnetic means in close proximity to the operating surface
means over the length thereof;
(b) the primary member includes: a plurality of laterally adjacent,
longitudinally extending and articulated ferromagnetic laminations,
the laminations having a longitudinally toothed surface that is
transversely arcuate to be complementary to the rail operating
surface means; electrical windings wound about selected groups of
teeth of the laminations as a LIM primary; compliant means adjacent
the laminations, capable of deformation under load and at least
partial recovery after load removal; power means for obtaining
electrical power continuously as the primary member moves along the
rail and supplying polyphase electrical current to the electrical
windings; and cooling means contained in the primary member for
continuously providing cooling fluid to the laminations during
operation of the primary member; and
(c) the means for providing pressurized fluid is adapted to inject
pressurized fluid at high velocity into the space between the rail
operating surface means and the compliant means to support the
primary member above the operating surface means and to provide a
minute pressurized magnetic and suspension gap between the primary
and secondary members for efficient linear motor operation.
The advantages of operation of the present invention active linear
motor in a fluid-film bearing suspension configuration are
particularly enhanced when the primary assembly is the moving
element on a simple passive concave or convex support guide rail
made of an electrical conducting material. This guide rail could be
a continuous aluminium pipe, an aluminium trough extrusion profile,
or a conductively clad steel or iron pipe member. In any case a
magnetic iron or steel backing can be used to increase the
magnetism effect of the induced currents set up in the rail by the
moving magnetic fields of the suspended primary element.
In the present invention the active linear motor primary elements
are contingent to a fluid-film suspension mounting of a moving
carrier platform which includes a relatively small pump or
compressor with a fluid recirculation means through heat
exchanger(s) and contaminant removal separator(s). An electrical
power collector system for the linear motor is required for
on-board powering. This system may typically involve a rectifier
and inverter for current phasing with a control system of developed
technology, along with a position sensing device such as an
encoder. The present invention includes an optional means of using
compliant fluid-film support for improved power collection.
The active primary linear motor of the present invention is
particularly useful in those applications which require simplicity
and efficiency of propulsion and braking operation for high speed
travel over relatively long distance with minimal contact and
maintenance. Applications could include multiple sequenced monorail
air-film units as prevalent in overhead industrial assembly
applications and in clean room or hygienic situations. The present
invention suggests that such air-film suspended and tracked active
primary linear motor systems are practical for extremely high
speeds.
The present invention eliminates many of the existing mechanical
and electrical limitations of mechanically suspended linear units
by making use of externally fluid pressurized hydrodynamic
compliant bearing principles for operating active type motors in a
direct suspension arrangement. Flexibility of the primary linear
motor assembly is a key requirement for operation in a compliant
fluid bearing suspension. Described herein are many improvements by
which the active primary element of a linear motor is incorporated
into a fluid bearing suspension system by being made flexible while
using a compliant pad layer and cover. An air-bearing and/or fluid
bearing suspension system never herebefore achieved is
provided.
At this point it should be mentioned that the specification
hereinafter describes the present invention in terms of an
air-bearing suspension or support system in which the active
suspension or support medium is compressed air. It is also
contemplated that in particular applications the system would work
equally well using a pressurized liquid, such as water, as the
active suspension or support medium. In its broadest form the
present invention is thus presented as a system relying on
pressurized fluid as the operating medium.
Improvements to electrical collector systems are also outlined
herein. Such systems can enhance a non-contact inductive type
electrical power pick-up system when applied to the air-film
concept to eliminate the need for any mechanical positioning of the
pick-up coil and virtually any physical contact in the entire
system.
It should be noted that mechanical pick-up power contacts are
prevalent at the present time but can be air-film guided and
supported in a mini air-film system using a curved non-conducting
support and guiding trough containing the power conductor strips
for localized electrical power transfer as supported on a suitable
loaded extension arm mounted on the active linear motor
platform.
Induction coil means for power pick-up can also be employed to
maintain the overall virtual absence of moving parts claim of the
present invention. The exception to this claim will be the use of
ancillary compressor and fan units. The present invention suggests
several additional configuration improvements which allow the
location and shielding of the induction pick-up coil primary
conductors for proper containment of high frequency current
radiation effects. As a result electrical powering of the system is
carried out with environmental and safety advantages in a compact
arrangement.
Also described are means of induced flow or forced flow primary
motor lamination core cooling by the pressurized air or fluid
supply as induced by inspirator or injector means in a closed-loop
internal recirculation path and through internal heat exchangers.
The induced injector flow should be directed onto extended motor
core lamination cooling fin plates so as to take advantage of
available thermal expansion cooling. Included in the fluid loop
circuit is a means of removing contaminants and impurities such as
water and oil vapours in compressed air by a separator/collector
means. These removal devices are common to compressed air or fluid
systems with discharge to a collector reservoir for periodic
emptying or if appropriate to the atmosphere.
Recirculation of pressurized fluid is not restricted to active
motors but can also be applied to passive linear motor systems. In
the passive systems, the rail length(s) could serve effectively as
the heat sink and could be combined with suitable radiator coolers
at the recirculating fan or pump. The pressurized suspension fluid
is recirculated through the multiplicity of rail profile ports by
induced or mechanical means resulting in a rather lengthy system
with continuous series internal cooling of the multiple linear
motors. The heat sink provision of the rails would have the feature
of rail heating for de-icing or drying as an inherent
advantage.
The active linear motor system support incorporates a full length
pad of cellulose web which allows interlocking motor core modules
to flex a limited degree as required for the compliancy requirement
of the suspension. A flexible air-bag mounting arrangement for the
primary linear motor assembly is a preferred means which in
combination with the cellulose support pad or alone provides the
compliant support for the flexing motor modules while also
providing a spring air-ride cushion and a fluid chamber for heat
pick-up from the motor module lamination extension fins as well as
a small reservoir supply for the suspension nozzles.
The air-bag or fluid-bag support can employ a separate pressure
supply. The suspension nozzles in this case would be supplied
through separate pipes or tubing or plenum mounting which piping or
plenum would then also be exposed to the cooling of the
recirculating air or fluid.
Linear motors are not limited to air cooling only but can also
readily employ liquid coolant for even greater thrust power duty
cycles and efficiencies. A variation of a means of liquid cooling
of linear motors in the public domain is the relatively impractical
use of copper tubing wound as the electrical core field winding of
the linear motor poles. In this case the coolant flows within the
conductor tube windings.
Nozzle mounting for the active linear motors can be exacting.
Teflon.RTM. or other non-magnetic and heat resistant small tubing
is run through each motor module for connection to individual
stainless steel or similar hypodermic tubing nozzles of generally
0.020 inch internal diameter mounted and fixed to the cover and
ground off flush with the cover at a narrow 29 degree or shallower
inclination to the rail surface and directed also at approximately
45 degrees to the rail centerline as it passes through the outside
module cover as described in U.S. Pat. Nos. 4,185,399 &
3,952,666 & 3,875,163 . In the present invention the nozzles
are fixed to the cover and are free to move with the cover while
offering very little limitation to cover movement freedom. Each
nozzle is connected to the heat resistant flexible tubing or from a
small diameter flexible header through the cellulose or like
compliant layering or directed to an adjacent small clearance
cavity of generally 0.5 inch diameter and 0.3 inches depth provided
in the cellulose. This cavity provides a further degree of nozzle
freedom and will contribute to desirable localized vibration or
jackhammering and dither effects for assisting in the air-film
propagation action.
The present invention embodies specific improvements to the primary
element of an active linear motor system using a cooling system and
power collector systems for operation in a compliant air-film
bearing mode with high thrust capabilities without the use of any
mechanical means to maintain a magnetic gap or guiding or cooling
or even power collector operation. Active linear motor technology
represents specific improvements to the application of air bearing
support and powering of conveying systems and high speed
transportation systems.
In particular there are described herein improvements to the
carrier active electromagnetic element as well as to cooling of
this element and further to electric power collection.
Location monitoring and speed control of the active linear motor
primary assembly are generally provided through encoder comb
markings along the guideway or laser doppler systems or satellite
position locators for wireless communication to a base station for
digital feedback computation in conjunction with an onboard
microprocessor. This is important for control of headway clearance
and for safety or trouble location in the overall transit system. A
remotely controlled directed shutdown automatically stops any
primary module and automatically applies inherent rail locking and
holding brake features.
Rail for the active primary linear motor system is generally
transversely convex as might be more common with pipe system
guideways as described in U.S. Pat. No. 3,952,666 although it is
possible to have the curved rail support surface transversely
concave as described in U.S. Pat. No. 5,128,569. It follows that
rail interaction can also take place on a top portion of the
outside convex surface of a pipe, a longitudinal sector of a pipe,
both the outside top and underside of a pipe, the internal concave
bottom of a pipe, or both the internal concave upper and lower
surfaces of a pipe sector.
Guiding is provided in all cases through the air-film suspension
interface of the curved linear motor iron core laminations and
compliant layer with polymer cover which mates and coacts generally
with the curved underneath adjacent surface of the support
rail(s).
Pressurized air from the small onboard compressor of generally 2 to
4 horsepower is cooled and is coursed through the core windings and
laminations prior to entry at high velocity into the suspension
air-film interface through the very small air nozzles in the
polymer cover of the compliant cellulose layers. Passageways
provided through or provided in the face of the core ferromagnetic
laminations of the linear motor allow the threading of the flexible
Teflon.RTM. or similar heat resistant tubing for direct connection
of compressed air through the cellulose layers and thence through
conjunctive holes, slits, pores or small bore hypodermic tube
nozzles angularly fixed in the polymer covering. The air supply
passing through the primary windings and laminations and compliant
coverings effectively provides extra cooling for the continuously
operating primary assembly. This embodiment alternatively makes use
of a separate piping header or plenum supply dedicated to the
suspension nozzles. In this case the separate header or plenum is
independent of the linear motor cooling fluid flow. Since nozzle
flow does not require any cooling of the heat of compression the
resulting cooling load reduction allows increased availability for
heat removal from the primary core for even more efficient
operation.
LIM cooling may be enhanced through the provision of extended core
lamination plates. Extended plates project proud of the top of
every two or three standard (shorter) lamination plates of each LIM
module. Transversely adjacent standard core plates are next to
evenly spaced extended plates providing exposed finned air passage
clearances for heat dissipation. Extended lamination plates are
manufactured with the upper portion not less than a quarter depth
more than standard lamination plates. The lamination plates
otherwise include a plurality of longitudinally spaced generally
rectangular teeth along the bottom operating portion which contain
the magnetic electrical pole windings to coact with the secondary
(support and guiding) element. A general mating profile of the
lamination plates to the curved secondary element is achieved by a
slight vertical displacement of the lamination plates relative to
each other as described in U.S. Pat. No. 5,128,569. Alternately the
lamination teeth can be of different depths so that the innermost
teeth have a lesser depth than the outermost laminations (for a
convex rail) or the final assembly of laminations may be machined
to provide the required matching pole face curvature. The addition
of the compliant filler material and cover completes the air
bearing requirement for coaction with the curved secondary
rail(s).
The side assembly surfaces of the core lamination plates can also
be provided with vertical or near vertical top to bottom grooves on
at least one side to allow compressed air flow between adjacent
plates to the compliant padding and polymer cover and even to the
air nozzles. This flow not only provides the necessary air for the
suspension interface but provides efficient additional cooling of
the linear motor core. The use of separate tube piping to each
nozzle is preferred, however, as pressurization of the entire
compliant layer system resulting from through-plate air flow
requires some reinforcing or venting to reduce cover ballooning.
This can be through additional nozzles in the compliant filler
cover or through clearances along the sides of the LIM core, either
of which could be wasteful of air.
Core lamination plates are assembled into separate modules which
have mating end profile projections and recesses so as to provide
interlocking and hinged sectionalizing of the linear motor core.
Specific radial clearances at the end faces of the modules allow
for slight relative flexing between adjacent modules for enhancing
an overall assembly compliancy. A relatively thick cellulose ply
pad, an air bladder, or a fluid bladder type spring loading system
facilitates the necessary flexing movement. The interlocking
extensions of the lamination plates assist in the magnetic flux
between modules. Alignment, vertical plane rotation, and magnetic
continuity are assured with the rounded pivotal projections of
alternate plates fitting tightly into slightly larger radius
rotational recesses of the next adjacent module. This pivoting
contact allows some vertical flexing without having to resort to
pinned hinges. The modules are held together in close contact by an
encircling external tension member such as a rubber band or by a
non-magnetic spring which does not hamper the flexing motion of the
interlocking core modules. Alternatively, hinge pins can be used to
eliminate the need for external tensioning and can be of
ferromagnetic material or non-magnetic brass or Teflon.RTM.
material.
Field windings of the active LIM are interconnected at the pivot
areas so as to permit a degree of movement of adjacent core
modules. One means of winding with flexing allowance is provided by
looping of the windings and the use of flexible encapsulation which
is available from those skilled in the art of manufacturing linear
motors.
Suitable flexible seal strips or rod "spaghetti" or tubing of near
plate thickness at each linear motor module interconnection reduce
or prevent air leakage through the module flex joints.
The LIM cooling recirculation system comprises a jet injector-type
venturi to induce and force the compressed air or fluid through the
core fins and subsequent heat exchanger(s). The heat exchanger(s)
remove both the heat of compression as well as the heat picked up
from the top core fins of each linear motor module. In the air
bladder springing system the injector recirculates the air while
adding sufficient make-up air to sustain the suspension air-film
nozzle flow. Of course it is recognized that electrically driven
fan or pump devices can be utilized to recirculate this cooling
compressed air or pressurized fluid. With an injector the
endothermic expansion reaction is of additional cooling advantage
especially if it takes place immediate to the LIM cooling fins.
Suitable filtering and separator means well known to those skilled
in the art of using compressed air or fluid flow are included in
the recirculation loop preferably at the coolest and lowest
velocity sections.
Removal of moisture and water and oil vapour from the recirculated
air can be achieved immediately after injector cooling by a typical
coalescent filtering separator bowl fixed below the injector and
flow venturi. Rotational vanes in the filter impart a rotational
spin to the flow to assist removal of the condensed moisture by
centrifugal effects and gravity to a small bottom sump. A
protruding "dry-pipe" air exit can preclude air droplet carryover.
Water removal bleed from the sump to an automatic discharge
commonly used in filters will allow for periodic visual inspection
of the water removal operation process. Water removal takes place
at the coolest part of the motor assembly, usually at the extreme
lower front.
Ferromagnetic core lamination plates of the primary element are
assembled to provide multiple teeth protrusions which are
electrically conductor wound to create a plurality of magnetic
poles which are energized in travelling field sequences usually by
the application of polyphase electrical current. Motion of these
magnetic poles relative to the electrical conductive metallic
secondary surface induces electrical currents in this surface. In
response to these current flows there are corresponding magnetic
fields set up according to well known electrical and moving
magnetic flux principles. Resulting strong attractive (or
repulsive) reaction between the primary field flux and secondary
surface flux provides powerful longitudinal thrust forces for load
movement on the guiding suspension pressurized air-gap. Radial
magnetic attractive forces are easily handled as a load surcharge
by the suspension.
High power performance is dependent upon the capability of handling
extremely high currents without undue heating of the primary
element winding insulation. Heat deterioration of the insulation is
accumulative and the so-called "Duty Cycle" is determined for each
motor design to limit accelerated deterioration. The higher this
rating--the higher the current rating and power capability of a
motor. Winding insulation cooling means of the present invention is
of paramount importance in the ability of the primary to handle the
high currents and powers.
Wire for the LIM primary windings is wound over two longitudinal
tubes which are withdrawn usually after encapsulation of the main
core. The removal of these tubes provides cooling air flow ports
right through the motor windings, as described in U.S. Pat. No.
5,128,569. Further cooling means for the present motors is provided
by the finned extensions of the core lamination plates which
release heat to the relatively cool recirculation air flow as
previously described.
The extension fins and the intermodule pivotal interlocking means
for core module articulation are kept free of epoxy encapsulation,
when used, by the use of special slotted seal blocks fitted during
the manufacturing process to cover those portions of the core
lamination plates which must be kept free of encapsulation. All
lamination projections which are to be free of epoxy are precoated
with release agent to facilitate seal block removal.
Compliant air bearing operation requires a small pad of cellulose
plies or like filler material between the linear motor pole faces
and a continuous longitudinal enclosing cover. The configuration of
the curved core face with the cover and filler plies is similar to
that of the minimum cellulose runners of U.S. Pat. Nos. 4,838,169
& 5,090,330. The filler and cover are formed from materials
that are capable of deformation under load and at least partial
recovery after the load has been removed and have the capability of
withstanding the high LIM operating temperatures and some
suspension transient seal area friction.
The sectionalized and interlocking laminations for articulation of
the linear motor core modules have a tendency to vibrate minutely
in sympathy with the frequency of the energizing current. Vibration
of this type can be desirable as it can lessen seal area friction
of the compliant cover with the effects known as stiction or
dither. Any audible noise present because of this effect will be
muffled by the cover and compliancy layers so as not to be an
intrusion to the normal very low audible levels of operation.
Means for ducting the compressed air through the core laminations
of the linear motor by angled cut slots in the plates is described
in U.S. Pat. No. 5,128,569 with general manufacturing methods being
disclosed therein. Unencapsulated LIM cores can be employed for the
LIM motors. The core laminations without epoxy encapsulation can
use plates with one side thereof having vertical or near vertical
grooving for through-core cooling air flow between adjacent
laminations. Alternative use of thin Teflon.RTM. or the like washer
spacers between lamination plates can allow through-flow of cooling
air but this also reduces the core ferromagnetic density and may
reduce the available thrust somewhat.
Active LIM units require that the guideway support contains or is
the secondary element for the electromagnetic co-action propulsion.
This guideway secondary member of curved profile is a usually a
binary metal rail as supported on grade, on elevated steel or
aluminum structures, or on other materials or structures such as
formed concrete. In all cases the guideways include electrically
conductive and magnetic sensitive materials. Some rails are clad on
the exterior with copper or aluminium or like electrical conducting
materials over ferromagnetic materials. The rail conductive
cladding for induced current capability also provides protection
from atmospheric oxidation of the suitable steel magnetic portion
of the secondary element. Carried to an extreme, a rail could be
the inside of a conductive pipe with ferromagnetic materials
positioned on the outside at positions of most effectiveness.
Claddings or support surfaces are selected with friction reducing
properties in mind and can be augmented with low friction coatings,
stainings or impregnations to further reduce seal area contact
friction of the moving primary compliant covering. Friction
reducing materials such as molybdenum disulphide powders or the use
of motorized cleaning or application devices such as rotary brushes
or wipers are options which can be included on the leading edge of
the moving primary motor assembly.
Motor power collector devices of the non-contact type are
preferred. With these, power supply conductors held in adjacent
rail protective enclosures are used for the secondary power current
supply. An air -film suspension arrangement for the collector
device has been described previously and can also be employed in a
similar assembly with the non-contact collector. A suspended
coil(s) assembly is attached to and moves with the primary linear
motor assembly. High frequency current is induced in the pick-up
coils in close proximity to the power conductors (electromagnetic
fields) somewhat similar to a reverse of LIM action but similar to
transformer operation. Induced currents are rectified and inverted
by onboard devices to the required polyphase cycle current for the
LIM motor thrust generation. High frequency of the primary supply
assures good coupling of the supply currents and the induced
currents of the power coils.
Environmental concerns are very important and are accommodated in
the general make-up of the collector portion of the present
invention. Special attention is made to confine any electromagnetic
wave influences generated. Aluminum grid plate or similar shielding
of the linear motor end windings precludes inadvertent induced
current problems with personnel or with motor coils in proximity to
the power supply conductors. Various remote mountings of the
collector coil arrangement reduce undesirable effects. Power
conductors are enclosed and shielded so as to contain the
electromagnetic fields. Use of extruded polymer supporting brackets
for conductors in a continuous manner for the entire rail length is
considered a safety provision. Electroplated or similar outside
surface metallic coating is provided on the conductor brackets with
multiple slot interruptions so that induced current continuity is
blocked, yet this coating serves to shield any radiation as well as
to inhibit and restrict any extraneous induced electric currents
and associated heating which may be set up in any adjacent metal
parts. Minor heating effects can be an advantage to heat the rails
for cold or freezer or icing conditions.
Other features of the present invention will be described hereafter
and with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a prior art passive LIM support and
conveying system showing a track system incorporating several
linear motor primary modules in accordance with present
developments of the passive pressurized air-gap linear motor
propulsion system.
FIG. 2 is a perspective view of the compliant runner support of the
present air-film suspension system showing the wound cellulose web
as wound around a central paperboard core and then covered by a
polymer sheet.
FIG. 3 is a composite transverse sectional view of a runner such as
in FIG. 2 but which has had a longitudinal pocket cut partially
into the wound cellulose web for the inclusion of ferromagnetic and
electroconductive plates to form the secondary of the passive LIM
system.
FIG. 4a is a perspective view of the basic passive type air-film
pressurized air-gap electromagnetic propulsion suspension system
showing the air nozzles of a typical concave support rail which
incorporates curved rail profile primary linear motors at intervals
therealong to impart thrust to a compliant runner which
incorporates the secondary coactive plates of the linear motor
system.
FIG. 4b is a comparative perspective view of the basic active type
air-film pressurized air-gap electromagnetic propulsion system of
the present invention in which the primary element of the linear
motor propels itself along the support using the conductive
properties and guiding trough profile of the rail for both the
secondary electromagnetic element and the suspension. Necessary
electrical power pick-up for the suspended primary linear motor
element is shown as an adjunct collector along the rail.
FIG. 5 is a sectional view of the active type pressurized air-gap
flexible primary linear motor system of the present invention
showing a compliant primary module mounting and a typical air-film
support and guiding rail with air nozzle supply of compressed air
to the rail secondary/runner primary interface and indicating the
inclusion of internal ferromagnetic plates in rail ports and the
adjunct power collector as attached to the rail. FIG. 5i shows an
inductive type non-contact pick-up system and FIG. 5ii shows a
spring-loaded sliding type pick-up more commonly used in present
day applications.
FIG. 6 is a another sectional view of the active type pressurized
air-gap flexible primary linear motor system of the present
invention showing a compliant primary module mounting and a typical
air-film support and guiding rail with air nozzle supply of
compressed air to the rail secondary/runner primary interface and
indicating the inclusion of internal ferromagnetic plates in rail
ports and the adjunct power collector as attached to the side of
the linear motor module in a more compact arrangement of a
non-contact inductive type pick-up.
FIG. 7a is an illustration of a prior art material handling
application in which an air-film suspension is used for the
indexing movement of goods on multiple cylinder driven
reciprocating air suspension platforms which co-act with air tube
type lifts for raising and lowering loads to accumulate and convey
such loads over distances of up to 200 feet. Multiple platforms
(usually five load capacity) are used; they are automatically
sequenced to transfer loads from platform to platform for high
density storage and staging. FIG. 7b is an illustration of a prior
art material handling application similar to that of FIG. 7a but
with the use of passive type linear motor powered movement (instead
of pneumatic cylinders) of only a single platform for essentially
the same load capacity. The single platform is programmed to
operate over the full 200 foot length of the conveying system for
the accumulation and staging and high density storage of unit loads
but more quickly and smoothly with virtually no moving parts.
FIG. 7c is an illustration of a prior art material handling
application similar to that of FIG. 7a and FIG. 7b but with the use
of active type LIM powered movement of the present invention
(instead of multiple pneumatic cylinders or multiple passive linear
motors) and using only one platform and one LIM system for reduced
complication and increased travel distances. The single platform of
the present invention is programmed to operate over the long
distances of the conveying system for the accumulation and staging
and high density storage of unit loads at each end of an extensive
travel distance, but more quickly and smoothly than any prior art
system and with virtually no moving parts.
FIG. 7d is a perspective view of an automated assembly line showing
an actual proposal for automotive assembly and skid handling using
pressurized air-gap passive linear motors. These could be replaced
by fewer active LIM units according to this invention.
FIG. 8 is a perspective view of an application directly suited to
the active pressurized air-gap linear motor propulsion system of
the present invention. A single monorail type load handling system
is shown as used extensively in large assembly plants such as
automotive factories.
FIG. 9 is a side view of the entirely self-contained active linear
motor prime mover showing the arrangement of the flexible primary
cores in accordance with the present invention with an air bag
mounting which incorporates a compressed air supply for both the
air-film nozzles and recirculation cooling.
FIG. 10 is a cross-sectional view of the active linear motor prime
mover showing a monorail assembly in co-action with a secondary
pipe type support.
FIG. 10a is a cross-sectional view of an active linear prime mover
showing a monorail assembly with a double, or upper and underside,
positioning of linear motor units in co-action with the same
secondary pipe type support rail. This arrangement in effect
doubles the thrust available with essentially the same (one)
pressurized air supply. The underside linear motor unit is
positioned against the secondary via a supplementary loading system
(in addition to the magnetic attraction usual with this motor) as
shown by the use of a flexible air bag spring mounting very similar
to that of the upper system.
FIG. 10b is a cross-sectional view of an active linear motor prime
mover showing a monorail assembly with a double, or lower and upper
positioning of linear motor units inside a pipe-like guideway and
co-acting with the same secondary partial pipe type support. This
arrangement in effect doubles the thrust available with the same
(one) pressurized air supply. The upper linear motor unit is
positioned against the upper inside concave surface of the pipe via
a supplementary loading system (in addition to the magnetic
attraction usual with this motor) as shown by the use of a flexible
bag spring mounting very similar to that of the lower system.
Ferromagnetic elements are attached to the outside of the
electrically conductive pipe material in positions appropriate for
the proper operation of the induced current thrust generation. The
continuous slot along the pipe provides only sufficient clearance
for the underslung "C"-shaped load support bracket so as to provide
the maximum section for structural strength and to also provide
maximum protection for the rail surfaces and power collector
flexible power pick-up mounting as described previously, located at
the backside inside surface.
FIG. 10c is a cross-sectional view looking from the front of dual
self-contained air-film suspended active pressurized air-gap LIM
propulsion units supported inside electrically conductive concave
partial pipe system monorails arranged in a mirror image type track
guideway with an extended carrier for load attachment outside and
above. In this example the propulsion units are shown with bracket
mountings to allow slightly canted LIM positioning for possible
additional stability at high speeds and to show that LIM propulsion
units need not always be mounted vertically. Each active LIM
propulsion unit has a second LIM propulsion unit mounted on top of
the pressurized air supply streamlined canopy and held to the upper
inside (underside) of each concave pipe of the track system as
described in FIG. 10b. The track guideway system comprises parallel
electrically conductive pipes of aluminum, also as described
previously in FIG. 10b. the use of interior pipe section guideway
rails is of particular advantages with grade ballasting in that the
support surfaces are almost fully protected from atmospheric
contaminants and they offer a saving in the ferromagnetic elements.
In addition, the power collector shown as an inductive non-contact
coil type is mounted at the extreme opposite side to the pipe slot
for maximum protection.
FIG. 11 is a perspective view of a self-contained monorail system
showing the linear motor primary core elements and compressed air
suspension and recirculation cooling of the interlocking LIM core
module laminations with the pivoting protrusion noses and recesses
of the laminations and the flexible core winding interconnections
which allow limited articulation of each module.
FIG. 12 is a cross-sectional detail of a self-contained monorail
active LIM system supported on a pipe rail assembly showing a
concave LIM core lamination module with the ancillary compressor
and recirculation cooling apparatus all mounted to one side
opposite the load connection yoke to effectively counter-balance
this yoke and to provide a flexible mounted power collector
platform.
FIG. 13 is an artistic sketch of an elevated pipe tracked people
and goods mover transportation system as might be used for rapid
transit in an urban setting.
FIG. 14 is an artistic impression of an elevated high speed
monorail vehicle module using active self-contained pressurized
suspension and air-gap LIM propulsion with power collector or
on-board gas turbine power source as might be employed for long
distance transportation.
FIG. 15 is an artistic impression of an application of the active
type linear motor propulsion as embodied in an elevator operation
in which there are no cables.
FIGS. 16a-16d are drawings of the active LIM core lamination plate
profiles which when assembled provide a curved face module while
allowing a small degree of individual module flexing with complete
overlapping for continuity of the magnetic flux flow and extension
firming for heat dissipation to atmosphere of pressurized fluid
coolant.
FIG. 17 is a side section showing the support platform with the air
bladder spring air flowing over the LIM extension cooling fins with
the compliant layer pad and polymer cover and the air jets exiting
through the cover into the suspension air-film cavity interface
with support surface.
FIG. 18 is a partial perspective view of a single nozzle with
compressed air supply flexible tube attached. A clearance cavity is
shown around the welded or screwed in place hypodermic or like
nozzle.
FIG. 19 is a sectional view of a single nozzle cavity showing the
nozzle hypodermic welded into the cover and that portion which has
been removed by grinding or other process flush with the outside of
the cover.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows the general arrangement of a typical SAILRAIL.RTM.
air-film bearing suspension system 10 for conveying unit loads 12
on typical parallel air-film trough rails 14 and 16. Rail 16 is
similar to rail 14 but is equipped with rail profile linear
induction motor (LIM) primary elements 18 incorporated as part of
and spaced along the rail 16. All rails and motors have a
transversely concave upper working surface 20 and all have a
plurality of longitudinally spaced angled nozzles 22 which extend
through the surface 20 to pass pressurized air from longitudinally
extending ducts 24 within the rails or from air plenums attached to
the underside of the motors to the surface 20. The teachings of
U.S. Pat. Nos. 3,875,163; 3,952,666; 4,185,399; and 5,128,569
relating to this technology are hereby expressly incorporated by
reference.
The load 12 is shown resting on a deck 26 which in turn is
supported by a pair of runners 28 and 30 which extend the length of
the deck 26 and are received in the corresponding rails 14 and 16.
As can be seen each of the runners 28 and 30 has a corresponding
convex lower operating surface 32 that is complementary in
curvature to the rail and motor working surfaces 20. The rail and
motor upper working surfaces 20 are collinear to ensure a smooth
transition of the runners 28 and 30 as the load travels along the
rails and primaries.
The runner 28 as shown in FIG. 2 is typical of a long length
compliant support air bearing runner with a continuous cellulose
ply 34 tightly wound around a circular core 36 and then compressed
flat by vertical loading onto a transversely concave form identical
to the working surface 20 with the resulting shape then being
covered with a polymer or similar cover sheet 38.
The runner 30 as shown in FIG. 3 is similar to runner having
cellulose 34 wound on previously round core 36, with the same
compressed shape and having a polymer sheet cover 38, but it
differs from the runner 28 in that the cover is of high temperature
capability such as Teflon.RTM. and a longitudinal pocket 40 is cut
into the outside underside convex portion of the cellulose to
closely accommodate thin ferromagnetic sheets 42 and thin electro
conductive sheets 44 of copper or aluminum which have been curved
to match the required radius to suit their juxtaposition in the
runner. These plates serve as the secondary element of the passive
linear motor in which the moving magnetic fields of the passive
primary induce electric currents in the conductive plates to set up
related magnetic fields in the ferromagnetic plates which co-act
with the travelling magnetic fields of the primary to produce
longitudinal thrust. The flexibility of these plates is important
with the application to the compliant air bearing usage and to this
end the ferromagnetic plates are slotted or segmented and taped
together to increase their vertical flexibility (especially with
curvature stiffening).
Also shown in FIG. 3 is a sectional view of a typical rail 14 or 16
showing the upper concave working surface 20 and internal
longitudinal ports 24 which supply air to nozzles 22. The nozzles
are angled in the rail working surface between LIM sections 18 but
are oriented essentially vertically within the LIM core plates as
shown within the superimposed LIM section 18. The LIM windings 46
and the blow-through cooling passages 48 for the compressed air
supply to the rail nozzles are shown also.
A comparison of the passive and active types of the compliant
bearing pressurized air-gap linear motors is illustrated
diagrammatically in FIG. 4a and FIG. 4b. In FIG. 4a runner 30 is
shown in air-film suspension with an extruded aluminum rail 16 and
nozzles 22 while being moved forwardly by its internal secondary
plates 42 and 44 in co-action with the stationary LIM primary
elements 18 in the rail. FIG. 4b shows an active LIM system of the
present invention in which the runner assembly 50 is air-film
suspended by the nozzles 22 in an extruded aluminum rail 14. This
runner contains flexibly hinged LIM primary modules 52 that
generate longitudinally travelling magnetic fields and induce
currents and corresponding magnetic fields in the extruded aluminum
rail 14, which fields in turn co-act with the LIM runner travelling
magnetic fields to produce a longitudinal thrust force. The active
LIM runner 50 is suspended and guided on the pressurized air at the
runner/rail interface as produced by air exiting the rail nozzles
22 and co-acting with the compliant covering 54 of the LIM modules
52. The power to the LIM runner is shown being supplied by an
electrical collector 56 in a protective insulated semi-enclosure 58
attached to the side of the rail. Ferromagnetic plates or bars or
the like 60 are inserted into the rail internal ports 24 to provide
the necessary magnetic reinforcement of the LIM secondary which in
this case is the continuous rail 14.
FIG. 5 is a cross section of an active LIM runner 50 of this
invention as assembled with a typical deck plate 26 and suspended
by pressurized air from nozzles 22 in aluminum rail 14. Alternative
power collector semi-enclosures are shown, with the usual sliding
spring loaded direct conductor contact type 62 or a newer inductive
type non-contact collector 64 with rigid pick-up devices 66 or 68
attached to the deck plate 26 by a bracket extension 70. The
flexibly hinged LIM modules 72 of the active runner 50 are
supported by an upper compliant cellulose pad 74 which allows
limited vertical intermodule movement of the hinged LIM modules 72.
The mounting brackets 76 of the LIM modules 70 are such that the
fastening bolts 78 of the LIM modules are free to move vertically
in slotted means provided in the brackets 76. The convex working
faces of the LIM modules are covered with a continuous pad 80 of a
minimal number of cellulose web plies 82 and a polymer outer cover
sheet 84. The ferromagnetic laminations 86 added inside the ports
of the rail 14 include air and control wire passages 88 to allow
air flow through the rails and to the nozzles.
FIG. 6 is an active LIM runner similar to that of FIG. 5 but with a
more directly connected power pick-up assembly 90 bolted by a
commonly used spline profile to match the side cavity of the rail
14. An inductive pick up 92 is connected to the runner by a bracket
extension 94.
FIGS. 7a and 7b are perspective sketches showing examples of how
LIM propulsion can be used to advantage in existing air-film
material handling systems. The example application shown is a
typical length of 100 feet and is usually installed on the floor of
a warehouse. Multiples of loads 96 are loaded into the system and
are moved and accumulated through the use of air-film suspended
moving platforms 98 which shuttle back and forth in floor (or rack)
mounted rails 14 and 16. Inflatable hose assemblies 100 lift the
loads 96 clear of, or lower the loads 96 onto, the platforms 98
which, with reciprocating movement in a programmed sequence,
intermittently move or accumulate these loads in an indexing manner
for staging or storage or conveying with a minimum of moving
parts.
FIG. 7a shows a present day pneumatic cylinder means 102 for moving
the platform 98 one load position space equal to the full stroke of
the cylinder. Movement is step-wise and relatively slow and
requires the use of multiple platforms (four in the case of the 100
foot length shown) with overlap transfer and position indicating
sensors all as operated from a central programmable control.
FIG. 7b shows a similar 100 foot length means for moving or
accumulation or staging or conveying multiple loads 96 except in
this case one of the support rails 16 for the single platform 104
contains ten (10) passive rail LIM primary units 18 as spaced 10
feet apart to co-act with at least one (1) platform runner 30
equipped with LIM secondary plates 42 and 44 as shown in FIG. 3. In
operation the single platform 104 moves on air-film rails 14 and 16
over the full 100 foot length of the conveying or accumulating or
staging system. Movement of a single platform is relatively fast
and continuous without the incremental reciprocation movement of
the FIG. 7a structure. Overall control is also achieved with the
use of a central control and location sensors or encoder devices or
doppler pulsed laser devices well known to those skilled in the
art.
The examples of FIGS. 7a and 7b have been described so as to
illustrate the advantages that can be gained by using passive LIM
primary units 18 instead of pneumatic cylinder operation means 102.
FIG. 7c illustrates the further advantages associated with using
only a single active LIM primary system 50 of the present invention
instead of ten (10) passive LIM 18 as shown in FIG. 7b.
FIG. 7c shows the rail 16 replaced by a rail 14 (without LIM units)
which is augmented with internal ferromagnetic secondary plates 86
and an attached power collector 56. The single platform 104 is
equipped with an active LIM unit 50 The use of only one active LIM
unit 50 over the requirement of ten (10) passive LIM 18 units and
all associated extra wiring and starters and sensors clearly
indicates the advantages of the active units of the present
invention in just this one example.
FIG. 7d is a perspective view of another example of an automated
line application of a multiple passive LIM 18 driven sled supported
assembly line with a return sled system indicated as proposed by an
large automotive manufacturer. Here the replacement of the multiple
passive LIM 18 rail units with only one active LIM 50 in each sled
should be apparent.
FIG. 8 is a perspective view of a further application of in-process
load handling in which a monorail adaption 106 of rail 14 supports
active self-contained LIM air suspension and thrust units 108 which
are analogous to active units 50. The unit 108 carries a hanger 110
which, in turn, supports the load 112. Active LIM units 50 have
been described previously in FIGS. 3, 5 and 6 and thus operation in
this monorail application is understood. However the self-contained
active LIM assembly 108 requires further explanation.
FIG. 9 is a side section view of an active self-contained LIM air
suspension and thrust unit 108 of the present invention. Here LIM
core ferromagnetic lamination modules 114 are pivotally interlocked
or mechanically linked to allow a limited amount of intermodule
vertical flexing. These modules are shown to carry a load platform
116 through the use of a flexible air-bag member 118. This platform
116 serves as the load support means as well as the base plate for
ancillary equipment which includes a small air compressor 120,
drive motor 122, a high pressure air cooler 124, and additional
serpentine cooling tubing 126 mounted in front of a compressed air
heat exchanger 138. The LIM core modules 114 are similar to the
pivotally assembled hinged modules 72 of compliant pad supported
systems previously described in FIG. 5 except that the
air-supported modules 114 include spaced apart laminations 128 each
of which has a vertical extension 130 protruding as a fin into the
air-bag member 18. The air provided by the compressor 120 is
circulated through system high pressure air injector 132 into the
air-bag member 118 for passage along the LIM core lamination
extensions 130 and then subsequently to a first precooling heat
exchanger 134. The air flows along passageway or conduit 136 to a
second heat exchanger 138 which is equipped with a cooling air fan
140. All of this air equipment and control box 142 (for power
conditioning and position response through an encoder pick-up
mounted with the collector device and the rail) is contained within
a streamlined cowling 144 equipped with louvred fore and aft
openings 146 and an air inlet filter 148. An air intake muffler and
filter 150 for the small system air compressor 120 supplies
relatively cooler external ambient air to the compressor 120 which
in turn supplies this air at 90 to 100 psig pressure as make-up air
for the system as required to maintain approximately a 40 psig
pressure for the air bearing suspension. The make-up air
compensates for air lost through leakage and through operation of
the nozzles of the air suspension system.
Compressed air required for the relatively few suspension nozzles
152 is fed through individual flexible supply tubes 154, core
lamination air passages 156, or holes 158 drilled through the LIM
core laminations 160 as shown in FIGS. 17, 18 & 19. The
compliant element 162 of the self-contained active LIM runner at
the support surface 164 of the concave rail 106 or convex (pipe)
rail 166 is similar to that described in FIG. 5 in that a thin
continuous compliant pad 170 extends over the working faces of the
LIM modules over which a high temperature polymer sheet cover 172
is installed, the nozzles 152 extending through the cover 172.
Injector 132 contains an outside insulated venturi throat 174 for
air velocity increase and corresponding pressure reduction
according to Bernoulli principles which enhances the general
pumping action of recirculation air as produced by the central high
velocity jet 176 of the high pressure (100 psig) air supply. At
this the already coolest part of the air recirculation system the
rapid expansion of the air from the jet 176 to the lower (40 psig)
air-bag pressure causes local expansion cooling according to
Boyle's principles and the lowering of pressure combined with
expansion cooling into a large expansion chamber 178 at this
coolest part of the system causes any water contained in the
compressed air to condense and drop out of the low velocity air
stream in this chamber. A projecting sharp angled (entry) air
outlet slot (commonly referred to as a so called "dry pipe"
configuration) 180 physically reduces water droplet carryover.
Further water droplet removal can be realized with the addition of
small baffles and coalescent filtering media in the expansion
chamber. Collected water is drained off from the bottom of the
expansion chamber 178 by various automatic means readily known to
those skilled in compressed air systems.
FIG. 10 is a cross-sectional view looking from the front of a
self-contained air-film suspended active pressurized air-gap LIM
propulsion unit 108 supported on a convex pipe system monorail 166.
The extensions 130 of the LIM core laminations 128 are easily
discernable with the high pressure air jet 176 and expansion
chamber 178 and exit slot 182 shown. The monorail ferromagnetic
pipe support 166 is shown with electric conductive cladding 184.
The load support "C"-shaped carrier or bracket 110 centres the load
forces symmetrically on the suspension system while allowing the
offset rail supports 186 to be attached to the rail and to a main
supporting structure (not shown).
FIG. 10a is a cross-sectional view looking from the front of a
self-contained air-film suspended active pressurized air-gap LIM
propulsion unit 108 supported on a convex pipe system monorail 166
with a second active pressurized air-gap LIM propulsion unit 109
mounted on an extended "C"-shaped carrier 111 and held to the
underside of the convex pipe system monorail by an inverted second
air-bag spring member 118 which applies the necessary loading and
floating mounting for a second LIM core assembly 192 to the pipe
system monorail. As only one module containing ancillary equipment
is used to supply both the upper 190 and lower core assemblies 192
of the suspension and propulsion system, an electrical and air
recirculation and make-up connection 113 is required to service the
lower unit.
FIG. 10b is a cross-sectional view looking from the front of a
self-contained air-film suspended active pressurized air-gap LIM
propulsion unit 108 supported inside an electrically conductive
concave partial pipe system monorail 185 with an extended
"C"-shaped carrier 115 for central load attachment outside and
below the monorail system and with a second active pressurized
air-gap LIM propulsion unit unit 187 mounted on top of the
propulsion unit 108 and held against the upper inside (underside)
of the concave pipe system monorail by a second air-bag spring
member 118 as inverted to apply the necessary loading and floating
mounting of a second LIM core assembly 193 to the pipe. As only one
module 190 containing ancillary equipment is used to supply both
the upper and underneath laminations-containing portions 193,167 of
the suspension and propulsion system an electrical and air
recirculation and make-up connection 195 is required to service the
upper unit. The monorail system comprises an electrically
conductive pipe of, for example, aluminum of at least 18 inches in
diameter, of which a full length longitudinal sector has been
removed to define a slot 191 to clear the extended "C"-shaped load
carrier system. Necessary ferromagnetic attachments 197 are affixed
to the outside convex surface of the pipe monorail at positions and
of suitable width as required to co-act with the active LIM units
inside the monorail. The mounting bracket 186 is of full depth of
the pipe so as to support the monorail on suitable column or wall
support structures as well as to hold the pipe circular tolerance,
as the pipe tends to open outwards with the section portion
removal. The use of the interior of a pipe section as the guideway
is of particular advantage in that the support surfaces are almost
fully protected from atmospheric contaminants and they offer a
saving in the ferromagnetic elements. In addition, the power
collector is mounted at the extreme opposite side to the pipe slot
and thus is protected to a considerable degree. It can be spring
mounted, air-bag mounted, or even air-film suspension mounted (not
shown).
FIG. 10c is a cross-sectional view looking from the front of dual
self-contained air-film suspended active pressurized air-gap LIM
propulsion units 108 supported inside electrically conductive
concave partial pipe system monorails 199 arranged in a mirror
image type track guideway with an extended carrier 117 for load
attachment outside and above. In this example, the propulsion units
are shown with bracket mountings 201 to allow slightly canted LIM
positioning for possible additional stability at high speeds and to
indicate that LIM propulsion units need not always be mounted
vertically. Each active pressurized air-gap LIM propulsion unit has
a second LIM propulsion unit mounted on top of it and held against
the upper inside (underside) of each concave pipe of the track
system as described in FIG. 1Ob. The track guideway system
comprises parallel electrically conductive pipes of, for example,
aluminum also as described previously. The use of interior pipe
section guideway rails is of particular advantage with grade
ballasting in that the support surfaces are almost fully protected
from atmospheric contaminants and they offer a saving in the
ferromagnetic elements. In addition, the power collector, shown as
an inductive non-contact coil type 92 is mounted at the extreme
opposite side to the pipe slot and is thus well protected.
FIG. 11 is a perspective view showing the assembly for further
clarification of the present invention air-bag spring member 118
and the need for the LIM core windings 188 to exhibit a degree of
flexibility between the LIM core modules.
FIG. 12 is a sectional view from the front showing an alternative
construction wherein ancillary equipment is mounted in a separate
module 190 to one side of the laminations-containing portion 192 to
act as a counterbalance to the load support 194 as well as to lower
the overall height of the assembly. The power collector system is
shown as a module 196 mounted separately underneath the air supply
and control module 190. A system for allowing limited float linkage
for this collector pick-up is indicated.
FIG. 13 shows a two pipe track support system 198 with elevated
supports 200. In this artistic rendering the active self-contained
LIM propulsion units 202 are configured as "people movers" and as
can be seen the present invention is clearly not restricted to
interior (factory) applications. The present invention is capable
of carrying loads of considerable weight.
FIG. 14 is an artistic perspective of a monorail-type
self-contained pressurized air-gap LIM propulsion system 204.
Various components of the system are shown in an exaggerated manner
for ease of comprehension. These components include the air-bag
spring 206, the flexible LIM module 208 and the compliant pad 210
having a high temperature flexible sheet cover 212. In this
embodiment a small gas turbine engine (not shown) is mounted inside
the streamlined cowling 214 and is capable of supplying additional
thrust if desired. The compressor stage bleed acts as a source for
compressed air and drives an on-board electrical alternator. This
alternator is used for the energizing the LIM for variable thrust
levels and speeds and provides power for a motor and an on-board
compressor to effect the necessary extensive cooling of the
flexible LIM primary system as operated on a long distance elevated
monorail LIM secondary. The secondary in this application is
provided by an elevated pipeline 216 having a ferromagnetic core
218 and an electrically conductive aluminum cladding 220.
FIG. 15 illustrates an artistic rendering of another application
for the pressurized air-gap active LIM drive of this invention. In
this case the application is an elevator system 222 in which
air-bag mounted LIM units 224 operate on both sides of vertical
pipe secondary elements 226 as shown or on a single central pipe
secondary (not shown) to completely eliminate the need for heavy
weights and speed limiting cables and headshaft drives, although a
simple counterweight system may be employed if desired. The
elevator cage is preferably streamlined in order to compensate for
the high vertical speeds achievable.
FIGS. 16a-16d are detail drawings of the LIM lamination core plates
used in this invention. Two types of core plates 230 and 232 are
shown, both being formed of a ferromagnetic material of about 1.3
mm in thickness and being provided with longitudinally alternating
generally rectangular teeth 234 and slots 236, the electrical
windings being directed through the slots of the assembled plate
modules as depicted earlier. In FIG. 16a the plates 230 are shown
with the teeth 234 and slots 236 located along the lower portion
thereof and with the upper portion having angled forward and
rearward edges 238 and 240 respectively. The angled forward edge
238 has a generally semi-circular recess 242 formed therein while
the angled rearward edge 240 has a generally semi-circular
protrusion 244 formed thereon, each protrusion 244 being adapted
for rotatable engagement with a corresponding recess 242 of a
longitudinally adjacent plate 230. The fit between the protrusion
244 and the recess 242 is fairly tight, while limited clearance
between adjacent angled edges 238 and 240 allows for a limited
degree of vertically rotational movement between longitudinally
connected plates 230.
FIG. 16b shows the other plates 232, which plates have rectangular
teeth and slots 234 and 236, respectively, identical to those of
the plates 230. The plates 232, however, are provided with vertical
extensions 246 which form the fin extensions 130 mentioned above
with respect to FIG. 9. The forward and rearward edges 248 and 250
of the plates 232 slope oppositely to the forward and rearward
edges of the plates 230 and with these plates the forward edge 248
is provided with a semi-circular protrusion 252 while the rearward
edge 250 is provided with a semi-circular recess 254, the
protrusions 252 and the recesses 254 serving the same purpose as
the protrusions 244 and the recesses 242 of the plates 230. The
first-described plates 230 are shown in dotted lines in FIG. 16c in
relation to the plates 232.
As seen in FIG. 16d the plates 232 are spaced apart so as to
alternate laterally with the plates 230 across the width of a
module 256, with the extensions 246 projecting upwardly so that
they can reside within the confines of an air-bag in the overall
assembly and thus be subjected to cooling air passing thereover as
previously described. While every second plate is shown as having
an extension 246 it is understood that more than one standard plate
230 could be positioned between spaced apart extended plates 232.
The teeth and slots of adjacent laterally adjacent plates are
aligned so that a plurality of slots extending the full width of a
module are created, which slots receive the electrical windings as
taught in U.S. Pat. No. 5,128,569. The windings that bridge the
intermodule gaps should not be wound overly tightly so that the
desired limited undulating movement of the modules relative to each
other is not hindered. That undulating movement is available
through the interengaging and alternating protrusion-in-recess
pivotal connections provided at each end of the modules. If
desired, the protrusions 244 and 252 can be provided with alignable
central apertures 258 which in turn receive a hinge-pin 260 to
connect (a) the laterally adjacent plates of one module together
and (b) to pivotally connect each module to a longitudinally
adjacent module.
As seen best in FIG. 16d the bottom surface of the teeth 262
defined by laterally adjacent plate teeth 234 are machined to have
a convex profile, which profile is complementary to the concave
trough or upper surface 20 of a rail 14 (for example). If the
lamination module is to be used in a LIM primary that will be used
on a convex rail (for example a pipeline-type monorail as in FIG.
14) the bottom profile of the module teeth 262 would be concave,
rather than convex.
FIG. 17 is a side view section showing the support platform 116
with the air passing along the interior of the air-bag spring 118
flowing over the lamination extension cooling fins 130. The
compliant layer pad 170 is shown, along with the polymer cover 172
and the air jets 264 exiting through the nozzles 152 provided in
the cover 172 into the suspension air-film cavity interface with
the appropriate rail support surface.
FIG. 18 is an enlarged partial perspective view of a single nozzle
152 with a flexible compressed air supply tube 154 attached
thereto. A clearance cavity 266 is shown as surrounding the welded
or screwed in place hypodermic or like nozzle 152. the flexible
tube 154 is seen as passing downwardly from the interior of the
air-bag 118 through a hole or gap 268 provided between an adjacent
pair of laminations within a module.
FIG. 19 is an enlarged sectional view of a single nozzle cavity 266
showing the hypodermic or like nozzle 152 welded into the cover 172
and that portion of the nozzle which extended beyond the outer
surface of the cover having been removed as by grinding or
otherwise so that the nozzle is flush with the outer surface of the
cover 172. Flexible tubing 154 as fed through the LIM module
laminations 128 is attached to the nozzle 152 in such a manner so
as to allow a degree of localized cover movement. The clearance
pocket or cavity 266 of not more than an inch diameter is cut in
the compliant pad 170 around the nozzle 152 to allow for additional
localized flexing or vibration.
The foregoing has described an active LIM propulsion and suspension
system which has numerous advantages and applications. It is
understood that a competent engineer could readily devise
alternative structures and applications without departing from the
spirit of the present invention. Accordingly the protection to be
afforded this invention is to be determined from the claims amended
hereto.
* * * * *